Bipolar batteries employ either one of two types of bipolar electrodes, i.e., face-to-face or side-by-side. Face-to-face type bipolar electrodes, utilize an electrolyte resistant, impervious, substantially planar, conductive septum having a first polarity active material on one face thereof and an opposite polarity active material on the opposite face thereof. It is known for the electrically conductive septum that separates the opposite polarity active materials of the bipolar electrode to comprise either (1) a thin metal plate (e.g., lead in the case of a Pb-acid battery), (2) an electrically conductive polymer, or (3) a nonconductive polymer having a plurality of rivet-like conductors embedded therein for electrically communicating one face of the septum to the other. For a number of reasons, the use of solid metal plates is preferred for long-lived, high power, bipolar batteries. A metal plate septum particularly useful for lead acid batteries is described in copending U.S. patent application U.S. Pat. No. 5,344,727 and assigned to the assignee of the present invention. Other metal or conductive septums are useful with other types of battery systems (e.g., alkaline batteries) as is well known in the art.
The bipolar electrodes are mounted in nonconductive frames and stacked together such that opposite polarity faces of adjacent bipolar electrodes oppose each other across an electrolyte-filled gap which also contains an electrolyte-permeable, dendrite-suppressing separator (e.g., microporous polyethylene, glass mat, microporous PVC, etc.). One such battery is exemplified by the patent to Poe et al 3,728,158, assigned to the assignee of the present invention.
The frames used to mount the bipolar electrodes are typically either clamped or adhesively secured together to form the finished battery. Neither are practical solutions to making such batteries. In this regard, clamping the frames typically adds extra weight to the system and results in an assembly susceptible to electrolyte leakage via any of the many seams between the many abutting frames. Adhesively securing the frames together on the other hand is extremely messy especially when coupled with all of the handling, alignment, and assembly requirements for so many individual components to form the finished battery.
It is an object of the present invention to provide a unique bipolar battery packaging arrangement for face-to-face type bipolar batteries which includes a plurality of bipolar electrodes each engaged on its perimeter by a nonconductive frame, wherein the frames are stacked together and embedded in a polymeric material molded in situ thereabout to seal the several seams and form the battery's housing. It is another object of the present invention to provide such a battery wherein the housing comprises a closed cell foam. It is a further object of the present invention to provide a unique method of assembling a gas-recombinant version of said battery having compressed fibrous glass mat separators of the type described in U.S. Pat. No. 3,862,861. These and other objects and advantages of the present invention will become more readily apparent from the detailed description thereof which follows.